WxJx :
Page caching is a way of speeding up subsequent requests, certainly. Whether it helped in your instance is impossible to know. It may be, but it might be someone else had requested that page earlier and it's still live.
When we're conducting the data capture phase of the work, we ensure we capture data while on a LAN, with no other applications running on the PC. And we tend to capture not just HTTP-based applications but SAP, RDBMS, and any other TCP application which a customer has which they think is crucial to their business, so the caching issue is less relevant there.
As an aside, it's interesting to see what apps customers think are critical. They always include "Email and web browsing" and I tend to say - "Nah, it's not vital".
Of course the major difference between the Internet and private circuits is we can give (and meet, for the most part) SLAs - try asking that of A-O-Hell !